doc: add the doc for min_write_recency_for_promote

Signed-off-by: Zhiqiang Wang <zhiqiang.wang@intel.com>

diff --git a/doc/dev/cache-pool.rst b/doc/dev/cache-pool.rst
index 2d22f1f3b7df08820b0e843a667ee382cc95c37b..7dc71c828e9ff7d3951b056957fed7fe7c2abba5 100644 (file)
--- a/doc/dev/cache-pool.rst
+++ b/doc/dev/cache-pool.rst
@@ -56,6 +56,7 @@ Set the target size and enable the tiering agent for foo-hot::
  ceph osd pool set foo-hot hit_set_period 3600   # 1 hour
  ceph osd pool set foo-hot target_max_bytes 1000000000000  # 1 TB
  ceph osd pool set foo-hot min_read_recency_for_promote 1
+ ceph osd pool set foo-hot min_write_recency_for_promote 1
 
 Drain the cache in preparation for turning it off::
 
@@ -114,14 +115,18 @@ between 0 and ``hit_set_count``. If it's set to 0, the object is always promoted
 If it's set to 1, the current HitSet is checked. And if this object is in the
 current HitSet, it's promoted. Otherwise not. For the other values, the exact
 number of archive HitSets are checked. The object is promoted if the object is
-found in any of the most recent ``min_read_recency_for_promote`` HitSets. ::
+found in any of the most recent ``min_read_recency_for_promote`` HitSets.
+
+A similar parameter can be set for the write operation, which is
+``min_write_recency_for_promote``. ::
 
  ceph osd pool set {cachepool} min_read_recency_for_promote 1
+ ceph osd pool set {cachepool} min_write_recency_for_promote 1
 
 Note that the longer the ``hit_set_period`` and the higher the
-``min_read_recency_for_promote`` the more RAM will be consumed by the ceph-osd
-process. In particular, when the agent is active to flush or evict cache objects,
-all hit_set_count HitSets are loaded into RAM.
+``min_read_recency_for_promote``/``min_write_recency_for_promote`` the more RAM
+will be consumed by the ceph-osd process. In particular, when the agent is active
+to flush or evict cache objects, all hit_set_count HitSets are loaded into RAM.
 
 Cache mode
 ~~~~~~~~~~

diff --git a/doc/rados/operations/cache-tiering.rst b/doc/rados/operations/cache-tiering.rst
index f53526600d3086b765e283fb951673f3101d4441..8275fe4381d39e694638a7bf801215a804e08266 100644 (file)
--- a/doc/rados/operations/cache-tiering.rst
+++ b/doc/rados/operations/cache-tiering.rst
@@ -193,14 +193,19 @@ between 0 and ``hit_set_count``. If it's set to 0, the object is always promoted
 If it's set to 1, the current HitSet is checked. And if this object is in the
 current HitSet, it's promoted. Otherwise not. For the other values, the exact
 number of archive HitSets are checked. The object is promoted if the object is
-found in any of the most recent ``min_read_recency_for_promote`` HitSets. ::
+found in any of the most recent ``min_read_recency_for_promote`` HitSets.
+
+A similar parameter can be set for the write operation, which is
+``min_write_recency_for_promote``. ::
 
        ceph osd pool set {cachepool} min_read_recency_for_promote 1
+       ceph osd pool set {cachepool} min_write_recency_for_promote 1
 
-.. note:: The longer the period and the higher the min_read_recency_for_promote,
-   the more RAM the ``ceph-osd`` daemon consumes. In particular, when the agent
-   is active to flush or evict cache objects, all ``hit_set_count`` HitSets are
-   loaded into RAM.
+.. note:: The longer the period and the higher the
+   ``min_read_recency_for_promote``/``min_write_recency_for_promote``, the more
+   RAM the ``ceph-osd`` daemon consumes. In particular, when the agent is active
+   to flush or evict cache objects, all ``hit_set_count`` HitSets are loaded
+   into RAM.
 
 
 Cache Sizing